Few Questions from PS and BS

[premed21]

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Hey, I have a couple questions from PS and BS sections:

1) There is a circuit which provides 12V. There is a resistor of 20 ohms The circuit has internal resistance of r. Both in parallel. If voltage drop for the 20 ohm resistor is 10 V, what is the resistance r?

2) What does binding in an "antisense" fashion mean?

3) A collagen defect would affect what parts of the body the most? (Extracellular matrix, intracellular matrix(?))

4) Can Sn2 occur only on an atom that has 4 single bonds (is tertiary), or can it also occur on an atom with 1 double bond and 2 single bonds?

5) In an o-chem passage doing extractions, which extraction method is better?
A. 1 because adding base before acid is better
B. 2 because adding acid before base is better.
C. Both are equally effective.

6) There is an XYZ plane. The electric field points X to Z. Where is magnetic field pointing to?

7) Where is magnetic field strongest between to magnets?

Thx in advance

 

[loveoforganic]

1) The current going in is the current going out, so the same current is going through both resistors.

V =IR; 10 = I*20; I = 0.5

now that we have the current, we can solve for the second resistor.

The voltage on either side of a battery must be equal.

12 - 10 = 2 V; 2 = 0.5*r; R = 4


4) single bonds

5) illogical without the pertinent question information

7) should depend on how they're oriented, shape of magnet, etc